Three-dimensional image capturing apparatuses that capture three-dimensional images in a state where binocular disparity is present (that is, capture a left eye image and a right eye image) are known; such apparatuses make it possible to reproduce a three-dimensional image in a display apparatus (called a “three-dimensional display apparatus” hereinafter) capable of projecting the three-dimensional image (the left eye image and the right eye image) independently for the left and right eyes, respectively.
In three-dimensional image capturing, a three-dimensional image (a left eye image and a right eye image) obtained in a state in which a high level of disparity is present between a far scene or long range (a subject in a background) and a near scene or short range (a subject in a foreground) will result in an image that exceeds the fusion limit for three-dimensional viewing by a person and is thus difficult to appear as three-dimensional, or an image that produces a feeling of fatigue in people who are viewing the three-dimensional image (a tiring image). In order to avoid generating such a poor three-dimensional image, there are techniques that obtain favorable three-dimensional images by performing disparity adjustment, stereo base adjustment (called “SB adjustment” hereinafter), and so on, and such techniques are widely used in professional three-dimensional image capturing for movies and the like.
Disparity adjustment is a technique used primarily in the case where a far scene or long range (a subject in a background) exceeds the fusion limit, and adjusting the disparity so that the distance to the background is compressed in a nonlinear manner brings the far scene or long range (the subject in the background) that was difficult to see three-dimensionally closer, making it possible to obtain a three-dimensional image that is easy to perceive in three dimensions (a three-dimensional image that can easily be seen in three dimensions).
On the other hand, stereo base adjustment reduces the space between two cameras (a camera for capturing a left eye image and a camera for capturing a right eye image) (that is, reduces the stereo base (interaxial distance)), making it possible to reduce the dynamic range of the disparity. For this reason, capturing a three-dimensional image after performing the stereo base adjustment described above makes it possible to obtain a three-dimensional image in which the entirety, from the far scene or long range (a subject in the background) to the near scene or short range (a subject in the foreground), is within a fusional area.
In addition, even in the case where the three-dimensional image is displayed in a display apparatus at a small size, the disparity of the three-dimensional image (that is, between the left eye image and the right eye image) is reduced, and thus the background is compressed. Accordingly, in this case, the three-dimensional image displayed in the small-size display apparatus is a three-dimensional image that is easy to view.
Employing the stated image capturing techniques (disparity adjustment, stereo base adjustment) in three-dimensional image capturing makes it possible to capture a three-dimensional image that is sufficiently easy to view (that is, a three-dimensional image that is easily perceptible in three dimensions) when displaying the image in three dimensions in a predetermined display environment (for example, see Japanese Patent No. 3157384).